1. Field of the Invention
The present invention relates to a sample tray to be used in an image information reader for reading the fluorescent image of a fluorescence-labeled sample and a fabrication method thereof.
2. Description of the Related Art
In the field of biological chemistry and molecular biology, a fluorescence detecting system using a fluorescent dye as a labeling material is hitherto known. According to this system, the evaluations of the arrangement of a gene, the expression level of a gene, the path and state of the metabolism, absorption, and excretion of an applied material in a laboratory mouse, the separation, identification, molecular weight, and characteristics of protein, etc. can be performed, by reading out information about the image of a sample distributing specific organism-originated materials labeled with a fluorescent dye.
For example, using the electrophoresis that causes a living cell in suspension or a biological compound (protein, etc.) in a solution to move to a positive or negative electrode through an electric field by the electric charge, a plurality of DNA fragments are electrophoresed on a gel support body, after a fluorescent dye has been added into a solution containing the plurality of DNA fragments. Alternatively, a plurality of DNA fragments are electrophoresed on a gel support body containing a fluorescent dye, or, after a plurality of DNA fragments have been electrophoresed on a gel support body, this gel support body is immersed into a solution containing a fluorescent dye. In this way, a gel support body (sample) distributing specific DNA fragments (organism-originated materials) labeled with fluorescence is obtained. With external light shielded, the obtained gel support body is irradiated with excitation light for exciting the fluorescent dye employed as a labeling material. The fluorescence emitted from the gel support body is photoelectrically read out. In this way, image information representing a distribution of DNA fragments labeled with fluorescence is acquired, and based on the acquired image information, a visual image is displayed on a display section such as a CRT display, whereby the evaluation of the molecular weight of the DNA fragment and the like can be performed.
Incidentally, in an image information reader to be used in the aforementioned fluorescence detecting system, a sample such as a gel support body is placed on a sample tray. This sample tray usually employs an aluminum sample tray processed with a black Alumite (or Alumilite) so that fluorescence is not erroneously detected.
However, once a fluorescent dye and the like adhere to the aforementioned sample tray, it will take substantial labor to rinse out the fluorescent dye completely. When it cannot be removed to the degree that does not have a bad influence upon fluorescence detection, fluorescence is erroneously detected and therefore the greatest attention must be paid in handling it and sometimes the sample tray cannot be reused.
Hence, a hybrid sample tray superimposing a flat glass pane on an aluminum plate processed with a black Alumite has been made. A sample is placed on the glass pane. However, ghosting is produced due to the reflection from the reverse of the glass pane and noise rises by irregular reflection. There are cases where unfavorable side effects are thus produced.
The present invention has been made in view of the aforementioned circumstances. Accordingly, it is an object of the present invention to provide a sample tray for an image information reader that is convenient to handle.
The sample tray of the present invention renders rinsing easy and can endure repeated use, by coating the placing surface of the sample tray with fluororesin.
That is, the sample tray according to the present invention is a sample tray on which a sample distributing specific organism-originated materials labeled with a fluorescent dye is placed and which is used in an image information reader having an excitation light source for emitting excitation light and photoelectric reading means for photoelectrically reading out fluorescence emitted from the fluorescent dye exited by the excitation light as a distributed image of the organism-originated materials in the sample and which employs the excitation light source, the sample tray, the sample, and the photoelectric reading means with an external light shield, wherein the sample tray has at least a surface on which the sample is placed coated with fluororesin.
Here, it is preferable that the fluororesin be, for example, a hybrid resin consisting of polytetrafluoroethylene (PTFE) and tetrafluoroethylene-perfluoroalkyl-vinylether copolymer (PFA) with a black color as a base. Specifically, it is preferable to employ Platinum stone (DuPont trademark (hereinafter omitted): Primer; 459-30170, Midocoat; 456-30270, Topcoat; 456-30370) with Silky Black (DuPont trademark (hereinafter omitted)) as a black pigment, 855-100 hybrid resin of PTFE and PFA (DuPont trademark (hereinafter omitted))with 855-023 industrial Primer (DuPont trademark (hereinafter omitted)) as a base, etc. In a conventional sample tray superimposing a glass pane on an aluminum plate processed with a black Alumite, ghosting from the glass pane or irregular reflection is mixed with fluorescence emitted from a sample and detected, so there is a limit in the case where fluorescent image information of high contrast is desired. On the other hand, for hybrid resin of PTFE and PFA with a black color as a base, there is no occurrence of ghosting or irregular reflection, because there is no need to superimpose a glass pane. As a result, fluorescent image information of high contrast can be acquired.
It is desirable for a user""s convenience that depressed or projected markings representing a readable range of the photoelectric reading means be formed in the surface of the sample tray of the present invention on which a sample is placed. Particularly, in the case where an image information reader can vary the angle of field, that is, the case where a distance between the photoelectric reading means and the sample tray is variable, markings can be used as a standard when a user disposes a sample within a reading range suitable to a distance between both, if the markings are formed such that they are suitable to each reading range corresponding to each distance between both. The sample tray with markings is thus convenient to use.
Note that the markings formed in a depression or projection formed in a sample tray itself can acquire an image signal more accurately than painted markings. That is, there are cases where some of the paints to be used in marking emit fluorescence in no small amount. When a sample is irradiated with excitation light, in such a case, fluorescence emitted from the markings is mixed with fluorescence emitted from the fluorescent dye contained in the sample, so that the mixture is photoelectrically read out as a noise component. On the other hand, in the markings formed by the depressed or projected configurations of a sample tray itself without employing such paint, there is no occurrence of such local noise and therefore an image signal can be acquired accurately.
As a sample, various forms, such as a gel support body and a membrane filter, a micro-titre plate, and a slide glass transferring this gel thereon, can be employed if specific organism-oriented materials labeled with a fluorescent dye are distributed.
The sample-tray fabricating method according to the present invention is a method of fabricating a sample tray on which a sample distributing specific organism-originated materials labeled with a fluorescent dye is placed and which is used in an image information reader which is equipped with an excitation light source for emitting excitation light and photoelectric reading means for photoelectrically reading out fluorescence emitted from the fluorescent dye by the excitation light as a distributed image of the organism-originated materials in the sample and which employs the excitation light source, the sample tray, the sample, and the photoelectric reading means with external light shield, the method comprising the steps of:
coating at least a surface, on which the sample is placed, with fluororesin; and
forming depressed or projected markings, which represent a readable range of the photoelectric reading means, on the surface on which the sample is placed.
Note that it is preferable that the fluororesin be a hybrid resin consisting of polytetrafluoroethylene (PTFE) and tetrafluoroethylene-perfluoroalkyl-vinylether copolymer (PFA).
According to the sample tray of the present invention, the sample-placing surface is coated with fluororesin. Therefore, even if fluorescent dye, a sample, etc. have adhered to the sample-placing surface, these can be rinsed out by simple washing. Thus, the sample tray of the present invention is easy to handle and can sufficiently endure repeated use.
In addition, according to the sample fabricating method of the present invention, depressed or projected markings are formed after the fluororesin has been coated. Therefore, as compared with the case where fluororesin is coated after formation of the markings, the occurrence of unevenness in the fluororesin coat thickness in the marked portions and the vicinities is less likely and therefore there is an advantage of reducing the influence on read image information caused by unevenness in the thickness of the fluororesin coat.
Furthermore, the process of coating fluororesin requires annealing to be performed at 400xc2x0 C. or so and this annealing process causes a sample tray to deform thermally. For this reason, after the annealing process, there is a need to correct this deformation by plastic deformation. However, since the aforementioned process of forming markings is performed after the coating process, the marking formation process and the thermal-deformation correcting process can be performed collectively. Thus, the number of processes can be reduced, compared with the case where a sample tray is fabricated in the order of the marking process, the coating process, and the correcting process.